Stamens as many as or twice as many as the petals, free or rarely numerous and in phalanges, inserted at the base of a disk; anthers 2-lobed at the base, sometimes with an apical gland; staminodes well-developed or vestigial or absent

Gynoecium

Ovary vestigial in the male flowers, in the female flowers of a single carpel which is sessile, subsessile or stipitate, 1-locular and 2-ovulate, or of 2–5 (7) carpels united for their full length and sessile or on a short or long gynophore, or slightly united at the base and by the stigma (otherwise free), each carpel 1-locular and 2-ovulate, or rarely 1–? ovulate; style long or short or absent, terminal or lateral; stigma capitate or discoid, ± deeply lobed

Fruits

Fruit baccate or drupaceous, 1–4-locular (1–3 loculi abortive), with 1-seeded loculi, or a 5-locular capsule with 2-seeded loculi, or 2-locular with 5–6-seeded loculi, or rarely a 1-seeded follicle

About 160 genera and 1,900 species of Rutaceae were recognised by Groppo et al. (2008), of which 48 genera and 350 species occur in the Neotropics (Kallunki 2004), 44-50 of these species belong to the genus Conchocarpus (Galipeinae).

Rutaceae is widely distributed in subtropical and tropical or less frequently in temperate regions of the world. In the Neotropics the family is more diverse in the understorey of moist forests, especially in Brazilian Atlantic rain forests (Galipeinae), but species of this group can also be found in drier areas (e.g. Casimiroa, Zanthoxylum, Balfourodendron and Helietta). Cneoridium, Thamnosma, and some Zanthoxylum, Ptelea and Choisya species occur in desertic or temperate areas in North America (Mexico); and the monospecific Pitavia occurs in temperate areas in Chile.Adiscanthus Ducke - native, 1 species, Amazon (Peru, Venezuela, Brasil).

In many Neotropical Rutaceae (all Galipeinae, Pilocarpus , Metrodorea , Raulinoa , Esenbeckia , Plethadenia , Peltostigma and Zanthoxylum ) the fruits are capsules or schizocarps with 1-5 dehiscent mericarps, many times with a detaching endocarp that ejects the seeds when mature, a mechanism analogous to that found in most Euphorbiaceae.

Tribe Galipeinae, the most diverse group of the Neotropics with 28 genera and c. 130 species, includes species with mostly zygomorphic flowers, a more or less tubular corolla, the filaments adnate to the corolla tube, and 2 (rather than 5) stamens and 3 staminodes.

Metrodorea , Esenbeckia , Helietta , Balfourodendron , Pilocarpus and Raulinoa are trees or shrubs with 1-3-foliolate (rarely simple or pinnate - some Pilocarpus ) leaves. They have small, actimorphic flowers, usually creamy white (some species with wine-red flowers in Pilocarpus and Metrodorea ). Raulinoa (endemic to Santa Catarina state, Brazil) are armed with thorns. Pilocarpus have racemose inflorescences, while the remaining genera have compound inflorescences (panicles or thyrses). Metrodorea and Esenbeckia have capsular fruits. Metrodorea have opposite leaves (like in some species of Esenbeckia ) with the sheaths of the opposite leaves joined at base with the upper part cucullate, protecting the apical branch bud. In Balfourodendron and Helietta the fruits are indehiscent and winged.

Casimiroa (Mexico and some parts of Central America) and Hortia (South America and Panama, most species in the Amazon) have baccate fruits. Casimiroa have palmately compound leaves and small, creamy-white flowers. Hortia have simple, usually large leaves (30-120 cm long) and pink flowers in large inflorescences.

Dictyoloma and Spathelia have small flowers with staminal filaments with hairy basal appendages as do some Simaroubaceae. Dictyoloma have 2-pinnate leaves and winged seeds. Spathelia are monopodial trees from the Amazon and Central America with large, 1-pinnate leaves crowded at the apex of the trunk as palms, and with samaroid fruits.

Key differences from similar families

Rutaceae can be confused with other families of Sapindales such as Meliaceae, Simaroubaceae or Sapindaceae because of the compound leaves, but they can be readily distinguished from these by the aromatic leaves with pellucid dots, which are scattered throughout the lamina or restricted to the margins.

There are several species of few-branched (frequently monopodial) shrubs from understorey of forested areas in Brazil and other countries with simple, large and alternate leaves that can be confused with other groups such as Clavija (Theophrastaceae), Pouteria (Sapotaceae) and member of the Euphorbiaceae.

Other important characters

Trees or shrubs, less often sub -shrubs or herbs.

Flowers usually actinomorphic and small, usually white or cream.

Intrastaminal disc usually present.

Fruits capsules or schizocarps with 1-5 dehiscent mericarps, often with a detaching endocarp that ejects the seeds when mature, a mechanism analogous to most Euphorbiaceae.

Rutaceae are best known by the exotic genus Citrus, because of its commercially consumed fruits. Other groups of the same subfamily of Citrus (Aurantioideae, see discussion above) are commonly cultivated as ornamentals in America, including species of Atalantia, Clausena, Murraya, and Swinglea.

Other extra-American cultivated genera are Dictamnus, Phellodendron, and Ruta.

Native species are used as commercial timbers, such as Euxylophoraparaensis Huber ("pau-amarelo"), Balfourodendronriedelianum (Engl.) Engl. ("pau-marfim"), both from Brazil, and Zanthoxylumflavum Vahl ("West Indian silkwood").

Species of Pilocarpus (the "jaborandis") are sources of the alkaloid pilocarpine, used to treat glaucoma: one of the species, P. microphyllus Stapf ex Wardlew. is commercially cultivated in Brazil. The bark of some species of Angostura, Galipea and Hortia are used to treat fevers. Casimiroa edulis La Llave & Lex. ("zapote blanco", "white-zapote") is cultivated for its edible fruits in Central America.

Notes on delimitation

The division of the family Rutaceae in seven subfamilies (Aurantioideae, Dictyolomatoideae, Flindersioideae, Rhabdendroideae, Rutoideae, Spathelioideae, and Toddalioideae) by Engler (1931) was based mainly on morphological characteristics such as degree of connation and number of carpels, fruit characteristics (e.g. dehiscent vs. indehiscent, fleshy or dry, winged or not) and histology of the glands with ethereal aromatic oil. Recent analyses using molecular, chromosomal, and phytochemical evidence have showed Aurantioideae as a monophyletic group, but not Rutoideae, Toddalioideae and Flindersioideae, and these groups must therefore be re-circumscribed.

The monogeneric Spathelioideae (Spathelia) and Dictyolomatoideae (Dictyoloma) are part of a larger clade containing African and European genera such as Bottegoa Chiov., Cedrelopsis Baill., Cneorum L., Harrisonia R. Br. ex A. Juss. and Ptaeroxylon Ecklon. & Zeyher. in a re-circumscribed and expanded Spathelioideae (see Chase et al. 1999 and Groppo et al. 2008 for a more detailed discussion).

Some Neotropical genera such as Conchocarpus Mikan and Esenbeckia Kunth appear not to be monophyletic, and studies treating their circumscriptions are currently underway.

Literature

Important literature

Chase, M.W., Morton, C.M. and Kallunki, J.A. 1999. Phylogenetic relationships of Rutaceae: a cladistic analysis of the subfamilies using evidence from rbcL and atpB sequence variations. American Journal of Botany 86: 1191-1199.